EV Battery Cooling Channel Designs in CAD

This article explores how electric vehicle (EV) battery pack cooling channels are designed and modeled using Computer-Aided Design (CAD). It outlines the primary channel configurations used for different cell types—including bottom cold plates, serpentine ribbons, and integrated module casings—while detailing the key geometric features and CAD-to-simulation workflows engineers use to balance heat dissipation, pressure drop, and structural packaging.

Common Cooling Channel Architectures

Cooling channels in EV CAD models are typically classified by their physical placement relative to the battery cells and their internal fluid-flow topologies.

  • Bottom Cold Plates (Extruded or Stamped): Most common for prismatic and pouch cell architectures, these plates sit beneath the cell modules. In CAD, they are modeled either as stamped aluminum sheet-metal assemblies joined via brazing, friction-stir welding, or laser welding, or as multi-port extruded profiles. The fluid pathways inside can follow parallel paths, serpentine paths, or U-turn loops.
  • Serpentine Ribbon Tubes: Predominantly used for cylindrical cells (such as 18650, 2170, and 4680 formats), these side-cooling channels snake between vertical columns of cells. In CAD, they are modeled using sweeping operations along complex splines to maintain maximum surface contact with the cell casings while accounting for tolerance gaps filled by thermal interface materials (TIM).
  • Inter-Cell Sandwich Plates: Thin cooling fins or mini-channel plates placed directly between adjacent pouch or prismatic cells. CAD models for these designs prioritize minimal thickness to maintain volumetric energy density while retaining internal structural integrity to withstand module expansion and swelling.
  • Structural and Immersion Channels: Advanced designs integrate cooling cavities directly into the structural battery enclosure (cell-to-pack or cell-to-chassis architectures). Immersion designs model cavities that flood the cell matrix directly with dielectric fluid, requiring CAD definition of distribution manifolds and drain passages rather than isolated tubes.

Flow Path Topologies within the Channels

Engineers manipulate internal channel geometry within CAD software to control fluid dynamics and heat exchange:

  • Parallel vs. Serpentine Networks: Serpentine channels provide longer fluid residence time but introduce higher pressure drops and thermal gradients across the pack. Parallel networks reduce pressure drop and maintain more uniform temperatures across modules, but CAD modeling must carefully dimension header manifolds to avoid uneven flow distribution among parallel branches.
  • Turbulence Promoters and Internal Fins: To disrupt laminar boundary layers and enhance convective heat transfer without drastically increasing flow rates, CAD models incorporate internal features such as micro-fins, pin arrays, dimples, or herringbone patterns inside the flow passages.
  • Variable Cross-Section Channels: CAD geometry is often optimized using parametric design to taper channel cross-sections. By narrowing the channel downstream as the coolant warms up, fluid velocity increases, which enhances the local heat transfer coefficient and offsets the reduced temperature differential between the coolant and the cells.

CAD Modeling Techniques and Simulation Integration

Designing cooling channels requires specialized CAD techniques to ensure manufacturability and readiness for computational fluid dynamics (CFD):

  • Fluid Volume Extraction: Modern battery CAD workflows require modeling both the solid channel walls and extracting the negative internal volume as a dedicated "fluid domain" body. This fluid domain is exported directly to CFD software to analyze Conjugate Heat Transfer (CHT).
  • Parametric Dimensioning: Channel widths, rib thicknesses, bend radii, and wall sections are parameterized to allow automated design-of-experiments (DoE) iterations driven by thermal and fluid simulation loops.
  • Manufacturing Constraints: Channel geometries modeled in CAD must reflect production methods. Stamped channels must incorporate appropriate draft angles and bend radii; extruded channels require uniform wall profiles; and brazed or bonded channels must include designated weld lands, adhesive channels, and leak-testing ports.